In 2008, just 31 percent of American 16-year-olds had their driver's licenses, down from 46 percent in 1983, according to a new study in the journal Traffic Injury Prevention. The numbers were down for 18-year-olds too, from 80 percent in 1983 to 65 percent in 2008, and the percentage of twenty- and thirtysomethings with driver's licenses fell as well. And even those with driver's licenses are trying to drive less; a new survey by car-sharing company Zipcar found that more than half of drivers under the age of 44 are making efforts to reduce the time they spend packed like lemmings into shiny metal boxes.

The decline in driving by younger Americans is fed by many factors: the high cost of gas and insurance at a time of economic insecurity; tighter restrictions on teen drivers in many states; and roads that are more congested than ever, making driving less fun than ever.

But the impact of the internet is big too. "It is possible that the availability of virtual contact through electronic means reduces the need for actual contact among young people," says Michael Sivak, research professor at the University of Michigan Transportation Research Institute and coauthor of the study on driver's licenses. "Furthermore, some young people feel that driving interferes with texting and other electronic communication."